java.lang.Object
- org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
- - org.eclipse.persistence.jpa.jpql.parser.AsOfClause

All Implemented Interfaces:

Expression
```
public final class AsOfClause
extends AbstractExpression
```
An AS OF clause is part of a flashback query, which provides ways to view past states of database objects, or to return database objects to a previous state, without using traditional point-in-time recovery.
Specify AS OF to retrieve the single version of the rows returned by the query at a particular change number (SCN) or timestamp. If you specify SCN, then the expression must evaluate to a number. If you specify TIMESTAMP, then the expression must evaluate to a timestamp value. Oracle Database returns rows as they existed at the specified system change number or time.
BNF: asof_clause ::= AS OF { SCN | TIMESTAMP } scalar_expression

Since:

2.5

Version:

2.5

Author:

Pascal Filion

Field Summary
- Fields inherited from class org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
  COMMA, DOT, DOUBLE_QUOTE, LEFT_CURLY_BRACKET, LEFT_PARENTHESIS, NOT_DEFINED, RIGHT_CURLY_BRACKET, RIGHT_PARENTHESIS, SINGLE_QUOTE, SPACE, UNDERSCORE
- Fields inherited from interface org.eclipse.persistence.jpa.jpql.parser.Expression
  ABS, ALL, AND, ANY, AS, AS_OF, ASC, AVG, BETWEEN, BIT_LENGTH, BOTH, CASE, CAST, CHAR_LENGTH, CHARACTER_LENGTH, CLASS, COALESCE, COLUMN, CONCAT, CONNECT_BY, COUNT, CURRENT_DATE, CURRENT_TIME, CURRENT_TIMESTAMP, DELETE, DELETE_FROM, DESC, DIFFERENT, DISTINCT, DIVISION, ELSE, EMPTY, END, ENTRY, EQUAL, ESCAPE, EXCEPT, EXISTS, EXTRACT, FALSE, FETCH, FIRST, FROM, FUNC, FUNCTION, GREATER_THAN, GREATER_THAN_OR_EQUAL, GROUP_BY, HAVING, IN, INDEX, INNER, INNER_JOIN, INNER_JOIN_FETCH, INTERSECT, IS, IS_EMPTY, IS_NOT_EMPTY, IS_NOT_NULL, IS_NULL, JOIN, JOIN_FETCH, KEY, LAST, LEADING, LEFT, LEFT_JOIN, LEFT_JOIN_FETCH, LEFT_OUTER_JOIN, LEFT_OUTER_JOIN_FETCH, LENGTH, LIKE, LOCATE, LOWER, LOWER_THAN, LOWER_THAN_OR_EQUAL, MAX, MEMBER, MEMBER_OF, MIN, MINUS, MOD, MULTIPLICATION, NAMED_PARAMETER, NEW, NOT, NOT_BETWEEN, NOT_EQUAL, NOT_EXISTS, NOT_IN, NOT_LIKE, NOT_MEMBER, NOT_MEMBER_OF, NULL, NULLIF, NULLS, NULLS_FIRST, NULLS_LAST, OBJECT, OF, ON, OPERATOR, OR, ORDER_BY, ORDER_SIBLINGS_BY, OUTER, PLUS, POSITION, POSITIONAL_PARAMETER, QUOTE, REGEXP, SCN, SELECT, SET, SIZE, SOME, SQL, SQRT, START_WITH, SUBSTRING, SUM, TABLE, THEN, TIMESTAMP, TRAILING, TREAT, TRIM, TRUE, TYPE, UNION, UNKNOWN, UPDATE, UPPER, VALUE, WHEN, WHERE

Constructor Summary

Constructors
Constructor Description

AsOfClause(AbstractExpression parent)
Creates a new AsOfClause.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`accept(ExpressionVisitor visitor)`	Visits this `Expression` by the given `visitor`.
`void`	`acceptChildren(ExpressionVisitor visitor)`	Visits the children of this `Expression`.
`JPQLQueryBNF`	`findQueryBNF(Expression expression)`	Retrieves the `JPQLQueryBNF` that represents the fragment of this `Expression` that was used when parsing the given `Expression`.
`String`	`getActualIdentifier()`	Returns the actual AS OF identifier found in the string representation of the JPQL query, which has the actual case that was used.
`String`	`getActualScnIdentifier()`	Returns the actual SCN identifier found in the string representation of the JPQL query, which has the actual case that was used.
`String`	`getActualTimestampIdentifier()`	Returns the actual TIMESTAMP identifier found in the string representation of the JPQL query, which has the actual case that was used.
`Expression`	`getExpression()`	Returns the `Expression` representing the timestamp or change number.
`JPQLQueryBNF`	`getQueryBNF()`	Returns the BNF of this `Expression`.
`boolean`	`hasExpression()`	Determines whether the `Expression` representing the timestamp or change number was parsed or not.
`boolean`	`hasScn()`	Determines whether the identifier SCN was part of the query.
`boolean`	`hasSpaceAfterCategory()`	Determines whether a whitespace was found after either SCN or `TIMESTAMP`.
`boolean`	`hasSpaceAfterIdentifier()`	Determines whether a whitespace was found after AS OF.
`boolean`	`hasTimestamp()`	Determines whether the identifier TIMESTAMP was part of the query.

Methods inherited from class org.eclipse.persistence.jpa.jpql.parser.AbstractExpression
children, getGrammar, getIdentifierVersion, getLength, getOffset, getParent, getQueryBNF, getRoot, isAncestor, orderedChildren, populatePosition, toActualText, toParsedText, toString

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - AsOfClause
```
public AsOfClause(AbstractExpression parent)
```
    Creates a new AsOfClause.
    
    Parameters:
    
    parent - The parent of this expression
- Method Detail
  - accept
```
public void accept(ExpressionVisitor visitor)
```
    Visits this Expression by the given visitor.
    
    Parameters:
    
    visitor - The ExpressionVisitor to visit this object
  - acceptChildren
```
public void acceptChildren(ExpressionVisitor visitor)
```
    Visits the children of this Expression. This method can be used to optimize traversing the children since a new list is not created every time Expression.children() is called.
    This does not traverse the Expression sub-hierarchy, use a subclass of AbstractTraverseChildrenVisitor in order to traverse the entire sub-hierarchy.
    
    Parameters:
    
    visitor - The visitor to visit the children of this object.
  - findQueryBNF
```
public JPQLQueryBNF findQueryBNF(Expression expression)
```
    Retrieves the JPQLQueryBNF that represents the fragment of this Expression that was used when parsing the given Expression.
    
    Specified by:
    
    findQueryBNF in interface Expression
    
    Overrides:
    
    findQueryBNF in class AbstractExpression
    
    Parameters:
    
    expression - The Expression that is a descendant of this one
    
    Returns:
    
    The JPQLQueryBNF that was used to parse the given expression
  - getActualIdentifier
```
public String getActualIdentifier()
```
    Returns the actual AS OF identifier found in the string representation of the JPQL query, which has the actual case that was used.
    
    Returns:
    
    The AS OF identifier that was actually parsed
  - getActualScnIdentifier
```
public String getActualScnIdentifier()
```
    Returns the actual SCN identifier found in the string representation of the JPQL query, which has the actual case that was used.
    
    Returns:
    
    The SCN identifier that was actually parsed, or an empty string if it was not parsed
  - getActualTimestampIdentifier
```
public String getActualTimestampIdentifier()
```
    Returns the actual TIMESTAMP identifier found in the string representation of the JPQL query, which has the actual case that was used.
    
    Returns:
    
    The TIMESTAMP identifier that was actually parsed, or an empty string if it was not parsed
  - getExpression
```
public Expression getExpression()
```
    Returns the Expression representing the timestamp or change number.
    
    Returns:
    
    The Expression that was parsed representing the timestamp or change number
  - getQueryBNF
```
public JPQLQueryBNF getQueryBNF()
```
    Returns the BNF of this Expression.
    
    Returns:
    
    The JPQLQueryBNF, which represents the grammar of this Expression
  - hasExpression
```
public boolean hasExpression()
```
    Determines whether the Expression representing the timestamp or change number was parsed or not.
    
    Returns:
    
    true if the timestamp or change number was parsed; false otherwise
  - hasScn
```
public boolean hasScn()
```
    Determines whether the identifier SCN was part of the query.
    
    Returns:
    
    true if the identifier SCN was parsed; false otherwise
  - hasSpaceAfterCategory
```
public boolean hasSpaceAfterCategory()
```
    Determines whether a whitespace was found after either SCN or TIMESTAMP.
    
    Returns:
    
    true if there was a whitespace after SCN or TIMESTAMP; false otherwise
  - hasSpaceAfterIdentifier
```
public boolean hasSpaceAfterIdentifier()
```
    Determines whether a whitespace was found after AS OF.
    
    Returns:
    
    true if there was a whitespace after AS OF; false otherwise
  - hasTimestamp
```
public boolean hasTimestamp()
```
    Determines whether the identifier TIMESTAMP was part of the query.
    
    Returns:
    
    true if the identifier TIMESTAMP was parsed; false otherwise

Class AsOfClause

Field Summary

Fields inherited from class org.eclipse.persistence.jpa.jpql.parser.AbstractExpression

Fields inherited from interface org.eclipse.persistence.jpa.jpql.parser.Expression

Constructor Summary

Method Summary

Methods inherited from class org.eclipse.persistence.jpa.jpql.parser.AbstractExpression

Methods inherited from class java.lang.Object

Constructor Detail

AsOfClause

Method Detail

accept

acceptChildren

findQueryBNF

getActualIdentifier

getActualScnIdentifier

getActualTimestampIdentifier

getExpression

getQueryBNF

hasExpression

hasScn

hasSpaceAfterCategory

hasSpaceAfterIdentifier

hasTimestamp